TMEM16A channels generate Ca2+‐activated Cl− currents in cerebral artery smooth muscle cells

Abstract

Transmembrane protein 16A (TMEM16A) channels are recently discovered membrane proteins that display electrophysiological properties similar to Ca2+‐activated chloride (ClCa) channels in native cells. The molecular identity of proteins that generate ClCa currents in smooth muscle cells of resistance‐size arteries is unclear. Here, using molecular biology and patch‐clamp electrophysiology we examined TMEM16A channel expression and characterized Cl− currents in arterial smooth muscle cells of resistance‐size rat cerebral arteries. RT‐PCR amplified transcripts for TMEM16A, but not TMEM16B‐K family members, in isolated pure cerebral artery smooth muscle cells. Western blotting of cerebral artery lysate using an antibody raised against TMEM16A revealed a band consistent with the predicted molecular weight of TMEM16A. Surface biotinylation and immunofluorescence indicated that TMEM16A channels are located predominantly within the arterial smooth muscle cell plasma membrane. ClCa currents recorded in arterial smooth muscle cells displayed properties similar to those of currents generated by recombinant TMEM16A channels expressed in HEK293 cells. A TMEM16A antibody and TMEM16A knockdown using siRNA both attenuated arterial smooth muscle cell ClCa currents. In conclusion, our data indicate that TMEM16A channels generate ClCa currents in cerebral artery smooth muscle cells.